Method of gaseously expanding hollow rivets



Dec. 27; 1949 KAHN 12,492,579

METHOD OF GASEOUSLY EXPANDING HOLLOW RIVETS Filed Aug. 11, 1941 IIVVENTO)? y WW'WJWZ 7%,;

ATTORNEYS Patented Dec. 27, 1949 UNITED STATES PATENT OFFICE METHOD OF GASEOUSLY EXPANDING HOLLOW RIVETS Bertrand B. Kahn, Cincinnati, Ohio, assignor, by mesne assignments, to United Air Lines, Inc., Chicago, 111., a corporation of Delaware Application August 11, 1941, Serial No. 466,395

(or. 21a-29) 6 Claims. 1

This invention relates to riveting, one object of the invention residing in a method of riveting providing high speed production of a riveted structure where only one side of the structure is readily accessible in the riveting operation.

Another object resides in a method of riveting in which the shank end of a headed rivet is subjected to an expansive action by a high internal pressure transmitting through the rivet from its headed end.

Another object is the provision of a method of riveting employing a rivet headed at one end and having a longitudinal passage terminating short of the unheaded end of the rivet, in which the headed end of the rivet is subjected to an explosive pressure applied from an exterior source and transmitted through the rivet to expand the unheaded projecting end.

Another object is the provision of a rivet, headed at one end and having a longitudinal passage terminating short of the unheaded end for transmitting pressure from the headed end to the unheaded end with resultant lateral expansion of the unheaded end.

Another object is the provision of a rivet headed at one end and having a longitudinal passage extending through the headed end and through the shank of, the rivet, but terminating short of the end of the shank which is adapted to expand over the surface of the structure from which it projects, and the headed end of the rivet having provision for subjecting the same to an instantaneous high pressure from a source coupled to the headed end.

Other objects and advantages of the invention will be apparent from the following description, the appended claims and the accompanying drawing.

In the drawing Fig. l is a sectional view through a rivet embodying the present invention and shown in its association with the portion of a structure to be riveted and with the end of a gun through which an explosive charge is transmitted;

Fig. 2 is a section through the rivet after the rivet has been expanded; and

Fig. 3 is a perspective view, partly in section, showing a gun applied to the headed end of the rivet.

Referring more particularly to the drawing, in which a preferred embodiment of the invention has been illustrated, like parts having been designated by the same reference numerals in the several views, In designates a structure to be riveted together by a series of rivets, one of which is shown at II. This structure 10 may, for example, be the covering of an airplane wing, the outer surface of which is readily accessible although the inner surface of the wing may be relatively inaccessible in the riveting operation so that access to the unheaded end of the rivet cannot be readily effected to expand the unheaded end in the customary manner. In'accordance with the present invention, however, the riveting operation is accomplished without backing up or pounding the rivet at its unheaded end.

The rivet, as shown in Figs. 1 to 3 inclusive,

comprises a shank l2 of cylindrical form and constructed of suitable riveting material. The length of the shank is such that the unheaded end of the rivet projects from the surface of the structure to be riveted, this unheaded end and the central portion of the rivet having a longitudinal passage l3 which terminates short of the unheaded end so that a wall portion l4 integral with the shank portion closes the unheaded end. At its opposite end the rivet is provided with a head 15, passage l3 extending through the head and preferably terminating in a conical seat l6 as shown more particularly in Figs. 1 and 2. Where the hollow shank portion projects from the surface of the structure to be riveted, at its unheaded end, the lateral wall portion [1 is of such thickness that its resistance to lateral expansion is less than its tensile strength in an axial direction so that when pressure is created inside the rivet the lateral wall portion I1 will bulge out laterally, the unheaded end of the rivet thus assuming a generally spherical form as indicated in Fig. 2 so that the parts of the structure Ill will be securely held to one another.

In accordance with the form of construction herein shown, the passage I3 is subjected to an instantaneous high pressure, applied from the headed end of the rivet, to expand the unheaded end of the rivet, this high internal pressure being applied by means of a gun I9 which has been shown more or less diagrammatically in Fig. 3. Fig. 1 illustrates the end of the gun barrel, indicated at 20, which is arranged in interfitting relation with the headed end of the rivet as by means of a conical seat surface 2| adapted to interfit with the conical surface IS on the rivet. The gun may be held by the operator by means of a handle 22 so that the end of the gun barrel may be pressed against the headed end of the rivet, and when a blank cartridge is exploded in the gun the explosive pressure is transmitted through the gun barrel through the head and to the interior of the rivet, applying a pressure on the inside of the rivet to expand the shank end of the rivet, without bursting the end wall It, and at the same time swell that part of the shank that extends through the plates to be assembled until this shank portion presses very firmly against the walls f the hole in the structure It. The rivet is thus made tight in its hole at the same timethe projecting end of the shank is headed. The gun is preferably of a repeating character, having a suitable trigger. 23 for firing the catridges. The cartridges may be supplied one after the other by means of a suitable cartride belt 24 to the firing chamber of the gun. The inertia of the gun due time required in a riveting operation is very small and limited only to the time required to insert the rivets and apply the end of the gun to the rivets successively. If it is desired to close the head end of the rivets after the riveting operation, for example to produce a more efiective streamlining of the rivet head, aluminum lacquer or suitable plastic material can be applied to the rivet heads.

As one example of a construction that has been satisfactorily employed, where rivets of diameter were used, the longitudinal passage in the rivet was made with a 38 gauge drill and the rivet was used in a hole of diameter so that the rivet could be very readily entered in the hole although afterit was expanded it fitted tightly against the wall of the hole. The explosive charge was such as to given an internal pressure of about 3,000 pounds per square inch.

While the method herein described and the form of apparatus for carrying the method into effect constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to this precise method and form of apparatus, but that changes may be made in either within the scope of the invention as described and defined in the appended claims without departing therefrom.

What is claimed is:

1. The method of riveting comprising inserting a headed hollow rivet in position in and with its unheaded end projecting from the structure to be riveted, applying an explosive pressure to the headed end of the rivet, and providing for transmission of the explosive pressure axially through the hollow rivet to the unheaded end thereof to expand the unheaded end over the surface of the structure.

2. The method of riveting comprising inserting a headed hollow rivet in position, with the unheaded end closed and projecting from the structure to be riveted, applying a gun to the headed end of the rivet, and explodin a charge in the gun in closed pressure relation with the hollow in said rivet to conduct the high pressure gases thus created through the rivet from its headed end tocexpand its unheaded end.

3. The method of riveting plates or the like 1 together, which consists in providing contiguous substantially aligned openings therethrough, inserting in said openings a rivet of material capable of acquiring a permanent set, said rivet having a head and a shank and a chamber extending axially from said head to a point near the end of the shank, the chamber in said shank extending beyond said plates a suflicient distance to permit the bulging of the side wall of said chamber into a head, and expanding said shank laterally into snug engagement with the walls of said openings and upsetting said exposed shank end against a plate-to form said head by introducing a gaseous fluid into said chamber and subjecting it to sufllcient pressure.

4. The method of riveting which comprises providing a rivet having in the shank thereof a cavity provided with a single access opening, inserting a nozzle in said opening to close the same, and forcing a gaseous fluid under pressure into the cavity through said nome.

5. The method of riveting plates or the like together, which consists in providing contiguous substantially aligned openings therethrough, in-

serting in said openings a rivet of material capable of acquiring a permanent set, said rivet having a head and a shank and a chamber extending axially from said head to a point near the end of the shank, the chamber in said shank extending beyond said plates a suflicient distance to permit the bulging of the side wall of said chamber into a head. and expanding said shank laterally into snug engagement with the walls of said openings and upsetting said exposed shank end against a plate to form said head by introducing a gaseous fluid into said chamber and subjecting it to suflicient pressure while applying heat to said shank through the medium of said fluid.

6. The method of riveting which comprises providing a rivet having in the shank thereof a cavity provided with a single access opening, in-

serting a nozzle in said openin to close the same, and forcing a gaseous fluid under pressure into the cavity through said nozzle while applying heat to said shank through the medium of said fluid.

BERTRAND B. KAI-IN.

REFERENCES CITED The following references are of record in the file of this patent: 1

UNITED STATES PATENTS Number Name Date 120,515 Harvey Oct. 31, 1871 446,466 Platt Feb. 17, 1891 1,400,401 Allan Dec. 13, 1921 1,415,124 Skelly May 9, 1922 1,770,071 Davis July 8, 1930 1,809,154 Becker June 9, 1931 1,945,480 Deems Jan. 30, 1934 2,045,126 Deems June 23, 1936 2,062,966 Buchholtz Dec. 1, 1936 2,092,358 Robertson Sept. 7, 1937 2,162,164 Febrey June 13, 1939 FOREIGN PATENTS Number Country Date 818121 France. June 7, 1937 

